Chromogenic crown ether reagents for spectrophotometric determinations of sodium and potassium

Crown ethers carrying a phenolic group, 2-hydroxyphenoxymethyl-15-crown-5 and -18-crown-6, were synthesized. Introduction of nitro groups in the 3- and 5-positions of the aromatic nucleus or introduction of a 4-nitrophenylazo group in the 5-position gives a series of chromogenic reagents suitable for the extraction spectrophotometry of sodium and potassium. Sodium in human blood serum was successfully determined by using the (2-hydroxy-3,5-dinitrophenyl)oxymethyl-15-crown-5 reagent. The molar absorptivity of the sodium complex is 14 000 l mol^-1 cm^-1 at 423 nm.     

Selective cleavage of polycyclic cyclopropanes by electrochemical oxidation

Anodic oxidation in acetic acid of polycyclic cyclopropanes, namely tricyclene, cyclofenchene, and longicyclene, followed by hydrolysis brought about stereo- and regioselective formation of the corresponding homoallylic alcohols as the main product in good yields.     

Measurement of high frequency ultrasound in liquids using high-resolution Bragg reflection technique

A new light scattering technique has been established for simultaneous measurement of ultrasonic velocity and absorption in liquids over a frequency range from 100 to 1000 MHz. The technique is applied to studies of vibrational relaxation in the uhf range, and the velocity-dispersion and absorption curves in several organic liquids are presented.     

XUV radiation transfer through high-Z metal foil in a laser-produced plasma

Aluminum and gold foils have been irradiated with 1.05-μm, 100-psec laser pulses at an intensity of 3 × 10¹⁴ W/cm². A spatially resolved spectrum of XUV radiation from a rear-side plasma has been observed in the wavelength range from 10 to 100 Å. The spectral intensity for the Al foil decays exponentially with foil thickness and goes to zero at 3 μm. The intensity for the Au foil also decays exponentially up to 1 μm but remains almost constant from 1 to 6 μm. This result for the Au foil indicates that radiation heat conduction plays an important role in energy transport through high-Z plasmas.     

Infrared-microwave double resonance in CH3OH using a Zeeman-tuned 3.5-μm HeXe laser

Infrared microwave double resonance signals have been observed for CH₃OH using the 3.5-μm HeXe laser line. When microwave transitions in the ground vibrational state are pumped, the double resonance signals are obtained on two infrared transitions v = 1 ← 0 of ν^CH(a′); v = 1, J, K, μ = 4, 2, 1 ← v = 0, J, K, μ = 3, 2, 1, and 4, 3, 1 ← 3, 3, 1. Three weak double resonance signals are due to the collision-induced transitions. Their relative intensities have been explained successfully by using the rate constants of collision-induced transitions which are proportional to the dipole matrix elements between the states involved in the transitions.     

Odd-even effect of the methylene chain number in the template polymerization of alpha,beta-diacetylenecarboxylates incorporated in layered double hydroxide clay

The present investigation reports on the significant differences observed in the efficiency of the polymerization depending on the odd- or even-numbered methylene chains of diacetylenecarboxylates, CH3(CH2)(m-1)C[triple bond]C-C[triple bond]C(CH2)(n-1)CO2- (mono-[m,n]), incorporated in layered double hydroxide (LDH) clay. Upon gamma-ray irradiation of the diacetylenecarboxylates, or mono-[m,n], in LDH clay, polymer hybrids or poly-[m,n]/LDH, which exhibited coloring from light orange to violet, were obtained. The color of the poly-[m,n]/LDH hybrids was strongly dependent on the extent of the polymerization degrees. Moreover, the polymerization degrees were controlled by the number of methylene spacers n between the carboxyl and diacetylene groups. An odd-numbered n for the methylene chain of mono-[m,n] was found to be the determining factor in the efficient polymerization of these self-assembling aggregates within the interlayers of LDH clay.     

Characterizations of isometric isomorphisms between uniform algebras via nonlinear range-preserving properties

Let be a surjective mapping from a uniform algebra on a compact Hausdorff space onto a uniform algebra on a compact Hausdorff space . Suppose that holds for every . Then we have that is an almost isometric isomorphism, which is a generalization of results of Molnár (2002) and Rao and Roy (2005).

     

Superconductivity of doped Ar@C60

The synthesis of a mg amount of pure argon containing fullerene allowed the synthesis of the first endohedral superconductors with critical temperatures lower than expected, an indication of the strong influence of the argon atom on the C60 cage.     

Analytical Solutions of Electromagnetic Fields from Current Dipole Moment on Spherical Conductor in a Low-Frequency Approximation

We analytically derive the solutions for electromagnetic fields of electric current dipole moment, which is placed in the exterior of the spherical homogeneous conductor, and is pointed along the radial direction. The dipole moment is driven in the low frequency f = 1 kHz and high frequency f = 1 GHz regimes. The electrical properties of the conductor are appropriately chosen in each frequency. Electromagnetic fields are rigorously formulated at an arbitrary point in a spherical geometry, in which the magnetic vector potential is straightforwardly given by the Biot- Savart formula, and the scalar potential is expanded with the Legendre polynomials, taking into account the appropriate boundary conditions at the spherical surface of the conductor. The induced electric fields are numerically calculated along the several paths in the low and high frequeny excitation. The self-consistent solutions obtained in this work will be of much importance in a wide region of electromagnetic induction problems.